Extraction and purification of oryzanol from rice bran oil and rice bran oil soapstock

Abstract

Oryzanol is an important value-added co-product of the rice and rice bran-refining processes. The beneficial effects of oryzanol on human health have generated global interest in developing facile methods for its separation from rice bran oil soapstock, a by-product of the chemical refining of rice bran oil. In this article we discuss the isolation of oryzanol and the effect that impurities have on its extraction and purification. Presented are the principles behind the extraction (solid-liquid or liquid-liquid extraction, and other methods) of these unit operations covered in selected patents. Methods other than extraction such as crystallization or precipitation-based or a combination of these unit operations also are reviewed. The problems encountered and the ways to solve them during oryzanol extraction, such as prior processing and compositional variation in soapstock, resistance to mass transfer, moisture content and the presence of surface active components, which cause emulsion formation, are examined. Engineering inputs required for solving problems such as saponification, increasing mass transfer area, and drying methods are emphasized. Based on an analysis of existing processes, those having potential to work in large-scale extraction processes are presented.Rice is the second-largest cultivated crop produced worldwide with current annual world production being approximately 583 million metric tons (1). Rice bran is one of the valuable byproducts of the rice processing industry (2). In many instances, it is economically feasible to extract oil from rice bran and purify it by physical and chemical refining for either food or industrial use. Owing to several technical and nontechnical problems in oil refining, the actual annual production of rice bran oil (RBO) does not meet demand (3). The major difficulties in processing crude RBO for edible purposes are its high levels of FFA, waxes, gums, and pigments. Accordingly, most RBO is used in nonfood applications. Chemical refining of RBO produces soapstock by-product (RBOS). The typical soapstock from RBO contains ~65-70 wt% water, 20-22 wt% soap, 2-2.5 wt% glycerides (mainly TG), and 7-7.5 wt% unsaponified matter. The unsaponified fraction contains ~42% sterols, 24% higher fatty alcohols, 20% oryzanol (as ferulic acid esters), 10% hydrocarbons, and 2% unidentified compounds (4). Oryzanol represents ~15% (2% of 7.5 wt%) of the unsaponified matter. At present, the major use of the soapstock is the generation of soap for the toiletry and detergent industries. It could also be used for production of therapeutically active components such as oryzanol and tocopherols (5). In view of the amount of oryzanol present in RBOS, which is generated in large amounts, there is an opportunity for commercial production of oryzanol from this by-product.Chemically, oryzanol is a mixture of ferulic acid esters of triterpene alcohols (phytosterols), i.e., ferulate (4-hydroxy-3-methoxy cinnamic acid) (6). The components of oryzanol were identified as ∆ 7 -stigmastenyl ferulate, ...

A Simplified Model to Describe the Kinetic Behavior of Supercritical Fluid Extraction from a Rice Bran Oil Byproduct

“…The determined RBOS mo isture content is lower than the ones reported by Narayan et al [17] (65 -70 %, w/w) and by Kaewboonnum et al [22] (57 %, w/ w). Such differences in the mo isture content are understandable since the RBOS co mposition depends on operational parameters of the RBO refining process, which usually differ fro m one industry to another.…”

“…The RBOS has been mostly used to produce soap by detergent industries. Nevertheless, this byproduct has a remarkab le potential o f being financially p rofitable since it could be used as a raw material fo r γ-ory zanol recovering processes [17]. The valuable antioxidant activity presented by γ-oryzanol makes it an interesting substance for wide application by food, cosmetic, and pharmaceutical industries.…”

Rice Bran Oil: A Versatile Source for Edible and Industrial Applications

“…The problems encountered and the ways to solve them during oryzanol extraction, such as prior processing and compositional variation in soapstock, resistance to mass transfer, moisture content and the presence of surface active components, which cause emulsion formation, should be examined. Engineering inputs required for solving problems such as saponification, increasing mass transfer area, and drying methods also should be carefully designed 18,19 . The TLC-densitometric and TLC-image analysis methods are useful for quantitative determination of γ-oryzanol in cold presses RBO 27 .…”

PROPRIEDADES LUBRIFICANTES DE GRAXA DE EXTREMA PRESSÃO (EP) DESENVOLVIDA A PARTIR DO RESÍDUO DO PROCESSAMENTO DE ÓLEO DE ARROZ (Oryza sativa L.)

“…Esta borra possui uma quantidade significativa de óleo, pois, durante o processo de desacidificação uma parte do óleo fica retida no sabão (NARAYAN; BARHATE; RAGHAVARAO, 2006). A destilação da BNOA para obtenção dos ácidos graxos gera o resíduo da destilação da borra de neutralização (RDBN).…”